Recently, as the security awareness is gradually increased, paper shredders are widely used in the offices of many companies. A paper shredder is an office machine used to cut a confidential paper document into plural small pieces (e.g. strips or fine particles) in order to prevent the confidential data of the document from being leaked. Generally, for most of the paper shredders, after the papers are manually fed into the paper shredders, the papers are cut into small pieces by the paper shredders. However, the number of papers that can be cut by the paper shredder is limited. If the number of papers exceeds the permissible paper number of the paper shredder at one time, the paper shredder is possibly jammed by too many papers or even the paper shredder has a breakdown or damage. For preventing from the breakdown or the damage of the paper shredder, the papers should be fed into the paper shredder in batches by the user. As known, the way of feeding the papers into the paper shredder in batches is time-consuming for the user. For solving the above drawbacks, a paper shredder with a function of feeding papers has been introduced into the market.
FIG. 1 is a schematic exploded view illustrating a conventional paper shredder with a function of feeding papers. As shown in FIG. 1, the conventional paper shredder 1 comprises a casing 10, an upper cover 11, an input tray 12, a shredding entrance 13, a feeding roller assembly 14, and a shredding knife assembly 15. The upper cover 11 is disposed on the casing 10. In addition, the upper cover 11 is rotatable relative to the casing 10 to be selectively opened or closed. When the upper cover 11 is closed, the casing 10 is covered by the upper cover 11. The upper cover 11 has a protrusion structure 111. When the casing 10 is covered by the upper cover 11, the protrusion structure 111 is coupled with the casing 10, so that the upper cover 11 is combined with the casing 10. The input tray 12 is disposed on the casing 10 for placing at least one paper (not shown) thereon. The shredding entrance 13 is disposed in the input tray 12 and located at a middle portion of the input tray 12. Through the shredding entrance 13, the at least one paper may be introduced into the casing 10. The feeding roller assembly 14 is disposed on the input tray 12, and located at bilateral sides of the shredding entrance 13. The feeding roller assembly 14 may be contacted with the at least one paper on the input tray 12 in order to feed the at least one paper into the shredding entrance 13. The shredding knife assembly 15 is accommodated within the casing 10 and disposed under the shredding entrance 13. When the at least one paper is transferred through the shredding entrance 13, the at least one paper is cut into small pieces by the shredding knife assembly 15. The casing 10 has a storage bin 101. The storage bin 101 may be slid relative to the casing 10 in order to be stored within the casing 10 or removed from the casing 10. When the storage bin 101 is stored within the casing 10, the storage bin 101 is disposed under the shredding knife assembly 15. Consequently, the small pieces of the at least one paper cut by the shredding knife assembly 15 are received within the storage bin 101.
The operations of the conventional paper shredder 1 with a function of feeding papers will be illustrated in more details as follows. After plural papers are placed on the input tray 12 of the paper shredder 1, the upper cover 11 is rotated relative to the casing 10 to have the upper cover 11 cover the casing 10, so that the upper cover 11 is combined with the casing 10 and the storage bin 101 is stored within the casing 10 (see FIG. 2). A way of placing plural papers S on the input tray 12 will be illustrated with reference to FIG. 3. FIG. 3 is a schematic perspective view illustrating the input tray of the conventional paper shredder. For clarification and brevity, only one paper S is shown on FIG. 3. In addition, the paper S is indicated as dotted lines.
Please refer to FIG. 3 again. As the feeding roller assembly 14 at the bilateral sides of the shredding entrance 13 is rotated, the papers which are contacted with the feeding roller assembly 14 will be fed by the feeding roller assembly 14. That is, the middle portion of the at least one paper S is contacted with the feeding roller assembly 14. The middle portion of the at least one paper S is firstly fed into the shredding entrance 13 by the feeding roller assembly 14. At the same time, the both ends of the at least one paper S are moved toward the shredding entrance 13. After the at least one paper S is introduced into the shredding entrance 13, the both ends of the at least one paper S are introduced into the shredding entrance 13. When the at least one paper S is transferred through the shredding entrance 13, the at least one paper S is cut into plural small pieces by the shredding knife assembly 15. Then, the plural small pieces fall down to the storage bin 101. After the plural papers on the input tray 12 are completely cut, the storage bin 101 may be removed from the casing 10, so that the plural small pieces within the storage bin 101 may be emptied by the user.
From the above discussions, the conventional paper shredder 1 with the paper feeding function can accommodate plural papers and cut the papers into plural small pieces. By simply placing plural papers on the input tray 12, the plural papers can be sequentially fed into the paper shredder 1 without the need of being fed in batches. However, the number of papers permissible to be accommodated within the input tray 12 of the conventional paper shredder 1 at one time is limited. In addition, the conventional paper shredder 1 has no function of prompting the user whether the overall thickness of the plural papers on the input tray 12 exceeds the maximum allowable thickness of the input tray 12. If the overall thickness of the plural papers on the input tray 12 exceeds the maximum allowable thickness of the input tray 12, the upper cover 11 is only able to cover the casing 10 but unable to be combined with the casing 10 because the overall thickness of the plural papers is too large. Under this circumstance, the user needs to exert an additional external force on the upper cover 11 in order to combine the upper cover 11 with the casing 10. After a long use time period, the upper cover 11 is readily fractured and the input tray 12 is possibly suffered from deformation in response to the external force. Since the feeding roller assembly 14 is disposed on the input tray 12, the operations of the feeding roller assembly 14 are adversely affected by the deformation of the input tray 12.
Therefore, there is a need of providing a paper shredder with an allowable thickness warning function.